Hong Kong was defensible only at prohibitive cost

How impossible was it to defend Hong Kong against China after the war?

It could be defended with enough fortification and outside support, but the required cost and commitment made that option strategically unrealistic.

The panel treats the Japanese capture of Hong Kong as evidence of its exposed geography and lack of territorial depth. Massive investment in fortifications, artificial defensive positions, redundant support, and offshore carrier air cover could make resistance possible. The duration of that defense would still depend on how much money and military capacity Britain was willing to commit against China. The practical conclusion is therefore not physical impossibility but an unfavorable relationship between cost, sustainability, and the value of holding the territory.